Electrolytes for lithium-ion batteries operating at extreme conditions

Abstract

Electrolytes for lithium ion batteries with carbon-based, silicon-based, or carbon-and silicon-based anodes include a lithium salt; a nonaqueous solvent comprising at least one of the following components: (i) an ester, (ii) a sulfur-containing solvent, (iii) a phosphorus-containing solvent, (iv) an ether, (v) a nitrile, or any combination thereof, wherein the lithium salt is soluble in the solvent; a diluent comprising a fluoroalkyl ether, a fluorinated orthoformate, a fluorinated carbonate, a fluorinated borate, a fluorinated phosphate, a fluorinated phosphite, or any combination thereof, wherein the lithium salt has a solubility in the diluent at least 10 times less than a solubility of the lithium salt in the solvent; and an additive having a different composition than the lithium salt, a different composition than the solvent, and a different composition than the diluent. In some electrolytes, the nonaqueous solvent comprises an ester.

We claim: 
     
         1 . An electrolyte, comprising:
 a lithium salt;   a nonaqueous solvent comprising a carboxylate ester, a carbonate ester other than ethylene carbonate (EC), vinylene carbonate (VC), or fluoroethylene carbonate (FEC), an orthoformate, a sulfate ester, an ether, a sulfone, a nitrile, or any combination thereof, wherein the lithium salt is soluble in the nonaqueous solvent;   a diluent comprising a fluoroalkyl ether, a fluorinated orthoformate, a fluorinated carbonate, a fluorinated borate, a fluorinated phosphate, a fluorinated phosphite, or any combination thereof, wherein the lithium salt has a solubility in the diluent at least 10 times less than a solubility of the lithium salt in the nonaqueous solvent; and   an additive having a different composition than the lithium salt, a different composition than the nonaqueous solvent, and a different composition than the diluent, wherein the additive does not consist of an organophosphate,   the electrolyte having a lithium salt-nonaqueous solvent-additive-diluent molar ratio of 1:x:y:z where 0.5≤x≤8, 0≤y≤2, and 0.5≤z≤5,   wherein if the nonaqueous solvent consists of one or more carbonate esters, the additive does not consist of fluoroethylene carbonate (FEC) or x/y>4.   
     
     
         2 . The electrolyte of  claim 1 , wherein the lithium salt comprises lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium (fluorosulfonyl) (trifluoromethylsulfonyl)imide (LIFTFSI), lithium bis(pentafluoroethanesulfonyl) imide (LiBETI), lithium trifluoromethanesulfonate (LiTf, LiCF 3 SO 3 ), lithium hexafluorophosphate (LiPF 6 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium bis(oxalato) borate (LiBOB), lithium difluoro (oxalato) borate (LiDFOB), Lil, LiBr, LiCl, LiSCN, LiNO 3 , LINO 2 , Li 2 SO 4 , or any combination thereof. 
     
     
         3 . The electrolyte of  claim 1 , wherein the nonaqueous solvent comprises dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), propylene carbonate (PC), 2,2,2-trifluoroethyl methyl carbonate (TFEMC) or methyl 2,2,2-trifluoroethyl carbonate (MTFEC), bis(2,2,2-trifluoroethyl) carbonate (BTFEC), difluoroethylene carbonate (DFEC), trifluoroethylene carbonate (TFEC), trifluoropropylene carbonate (TFPC), ethyl acetate (EA), ethyl propionate (EP), methyl butyrate (MB), propyl propanoate (PP), ethyl trifluoroacetate (ETFA), 2,2,2-trifluoroethyl acetate (TFEA), 2,2,2-trifluoroethyl trifluoroacetate, or any combination thereof. 
     
     
         4 . The electrolyte of  claim 1 , wherein the nonaqueous solvent comprises EP, DMC, PC, or any combination thereof. 
     
     
         5 . The electrolyte of  claim 1 , wherein the additive comprises ethylene carbonate (EC), fluoroethylene carbonate (FEC), vinylene carbonate (VC), 4-vinyl-1,3-dioxolan-2-one (vinyl ethylene carbonate, VEC), 4-methylene-1,3-dioxolan-2-one (4-methylene ethylene carbonate, MEC), 4,5-dimethylene-1,3-dioxolan-2-one, prop-1-ene-1,3-sultone (PES), 1,3,2-dioxathiolane-2-oxide, 1,3,2-dioxathiolane-2,2-dioxide, 1,3,2-dioxathiane-2,2-dioxide (DTD), lithium bis(oxalato)borate (LiBOB), lithium 2-trifluoromethyl-4,5-dicyanoimidazole (LiTDI), lithium difluoro(oxalato) borate (LiDFOB), lithium hexafluorophosphate (LiPF 6 ), lithium difluorophosphate (LiDFP), LiBF 4 , LIDFOB, ethylene sulfate(ES), propane sultone (PS), 3-methyl-,4,2-dixoazol-5-one (MDO), tris(2,2,2-trifluoroethyl) phosphite (TTFEPi), 2-oxo-1,3,2-dioxathiane, butanedinitrile, pentanedinitrile, hexanedinitrile, tris(pentafluorophenyl) phosphine, 1-methylsulfonylethene, 1-ethenylsulfonylethane, or any combination thereof. 
     
     
         6 . The electrolyte of  claim 1 , wherein the diluent comprises 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), bis(2,2,2-trifluoroethyl) ether (BTFE), 1H,1H,5H-octafluoropentyl 1,1,2,2-tetrafluoroethyl ether (OTE), 1,2,2,2-tetrafluoroethyl trifluoromethyl ether, heptafluoroisopropyl methyl ether, tris(2,2,2-trifluoroethyl) orthoformate (TFEO), bis(2,2,2-trifluoroethyl carbonate), tris(2,2,2-trifluoroethyl) borate, tris(2,2,2-trifluoroethyl) phosphate, or any combination thereof. 
     
     
         7 . The electrolyte of  claim 1 , wherein:
 (i) the additive comprises EC, FEC, LiDFP, LiPF 6 , or any combination thereof; or   (ii) y is 0.1-1; or   (iii) both (i) and (ii).   
     
     
         8 . The electrolyte of  claim 1 , wherein:
 (i) y=0.15-0.35; or   (ii) x+y=1.0-5; or   (iii) z=1-3; or   (iv) any combination of (i), (ii), and (iii).   
     
     
         9 . The electrolyte of  claim 1 , wherein the electrolyte has a lithium salt to nonaqueous solvent molar ratio of 0.2 to 0.75. 
     
     
         10 . The electrolyte of  claim 1 , wherein:
 (i) the salt comprises LiFSI; or   (ii) the solvent comprises DMC or the solvent comprises EP, and the electrolyte has a LiFSI to EP molar ratio of 0.2 to 0.75; or   (iii) the diluent comprises TTE, BTFE, OTE, TFEO, or any combination thereof; or   (iv) the additive comprises EC, FEC, LiDFP, LiPF 6 , or any combination thereof; or   (v) any combination of (i), (ii), (iii), and (iv).   
     
     
         11 . The electrolyte of  claim 1 , wherein the electrolyte has an FEC concentration from 0 mol % to 5 mol %. 
     
     
         12 . The electrolyte of  claim 1 , wherein the electrolyte does not comprise FEC. 
     
     
         13 . The electrolyte of  claim 1 , wherein:
 the salt comprises LiFSI;   the solvent comprises EP, DMC, PC, or any combination thereof, wherein if the solvent comprises EP, then the electrolyte has a LiFSI to EP molar ratio of 0.2 to 0.75;   the additive comprises EC, EC and LiDFP, or EC and LiPF 6 , and   the diluent comprises TTE.   
     
     
         14 . The electrolyte of  claim 1 , wherein the electrolyte consists essentially of the lithium salt, the solvent, the diluent, and the additive. 
     
     
         15 . A battery system, comprising:
 an electrolyte according to  claim 1 ;   an anode, where the anode is a carbon-based anode, a silicon-based anode, or a silicon/carbon composite-based anode; and   a cathode.   
     
     
         16 . The battery system of  claim 15 , wherein:
 the cathode comprises LiNi x Mn y Co z O 2  (x+y+Z=1), LiCoO 2 , LiMn 2 O 4 , LiFePO 4 , or LiNi 0.5−y X y Mn 1.5 O 4  (X═Fe, Cr, Zn, Al, Mg, Ga, V, Cu; 0≤y<0.5), Li 1+w Ni x Mn y Co z O 2  (x+y+z+w=1, 0≤w≤0.25), LiNi 0.8 Co 0.15 Al 0.05  O 2 , LiM C1   x MC 21   x PO 4  (M C1  or M C2 =Fe, Mn, Ni, Co, Cr, or Ti; 0≤x≤1), Li 3 V 2−x M 1   x (PO 4 ) 3  (M 1 =Cr, Co, Fe, Mg, Y, Ti, Nb, or Ce; 0≤x≤1), LiVPO 4 F, LiM 1   x M 2   y  (PO 4 )F (M 1  and M 2  are independently Cr, Co, Fe, Mg, Y, Ti, Nb, or Ce; 0≤x≤1; 0≤y≤1), LiM C1   x M C2   1−x O 2  ((M C1  and M C2  independently are Fe, Mn, Ni, Co, Cr, Ti, Mg, or Al; 0≤x≤1), LiM C1   x ,M C2   y ,M C3   1−x−y O 2  ((M C1 , M C2 , and M C3  independently are Fe, Mn, Ni, Co, Cr, Ti, Mg, or Al; 0≤1; 0≤y≤1), LiMn 2−y X y O 4  (X═Cr, Al, or Fe, 0≤y≤1), LiNi 0.5−y X y Mn 1.5 O 4  (X=Fe, Cr, Zn, Al, Mg, Ga, V, or Cu; 0≤y<0.5), xLi 2 MnO 3 ·(1−x) LiM C1   y M C2   z M C3   1−y−z O 2  (M C1 , M C2 , and M C3  independently are Mn, Ni, Co, Cr, Fe, or mixture thereof; x=0.3-0.5; y≤0.5; z≤0.5), Li 2 M 2 SiO 4  (M 2 ═Mn, Fe, or Co), Li 2 M 2 SO 4  (M 2 =Mn, Fe, or Co), LiM 2 SO 4 F (M 2 =Fe, Mn, or Co), Li 2−x (Fe 1−y Mn y )P 2 O 7  (0≤y≤1), Cr 3 O 8 , or Cr 2 Os; and   the anode is a graphite-based anode, a silicon-based anode, a silicon/graphite composite-based anode comprising 10 wt % to 90 wt % graphite and 5 wt % to 90 wt % silicon, or a silicon/graphite composite anode comprising carbon-coated silicon with a carbon content of 5 wt % to 55 wt %.   
     
     
         17 . The battery system of  claim 15 , wherein the battery system exhibits:
 (i) a first cycle Coulombic efficiency of at least 75%; or   (ii) an average Coulombic efficiency of at least 98% over 500 cycles at 25° C. after three formation cycles; or   (iii) an average Coulombic efficiency of at least 99.7% after 200 cycles; or   (iv) a capacity retention of at least 80% after 500 cycles at 25° C. compared to the first cycle after three formation cycles; or   (v) a capacity retention of at least 90% from 350 th  cycle to 500 th  cycle; or   (vi) any combination of (i), (ii), (iii), (iv), and (v).   
     
     
         18 . The battery system of  claim 15 , wherein:
 the lithium salt comprises LiFSI;   the solvent comprises DMC or the solvent comprises EP and the electrolyte has a LiFSI to EP molar ratio of 0.2-0.75;   the diluent comprises TTE; and   the additive comprises EC, FEC, LiDFP, LiPF 6 , or any combination thereof.   
     
     
         19 . The battery system of  claim 15 , wherein:
 the anode is a silicon-based or silicon/carbon composite-based anode; and   the electrolyte has a FEC concentration of 0 mol % to 5 mol %.   
     
     
         20 . The battery system of  claim 15 , wherein:
 (i) the battery system is operable at a voltage of 2.5 V to 4.5 V; or   (ii) the battery system is operable at temperatures ≥45° C.; or   (iii) the cathode has a specific areal capacity ≥3 mAh cm −2 ; or   (iv) any combination of (i), (ii), and (iii).